Security systems and/or security alarm systems often use magnetic switches attached to doors, windows, and other structures to detect the unauthorized opening and/or manipulation of the door, window, or other structures. However, previous magnetic switch designs have been prone to tampering, have exhibited unacceptable reliability, and/or are inflexible regarding the manner in which the magnetic switch couples to the door, window, or other structure.
Magnetic switches use the detection of a magnetic field and/or the absence of a magnetic field to indicate that a door, window, or other enclosure access has been opened. In its simplest form, a magnetic switch uses permanent magnet mounted to an enclosure access, e.g. a door to a room, and a magnetic sensor, such as a reed switch, to detect the presence or absence of the permanent magnet. If the magnet is detected, then the door is in the expected position. If no magnet is detected, then the door is not in the expected position. This go/no-go signal can be used as an input to an alarm system, automatic monitoring systems, and/or safety interlocks.
The effectiveness of the magnetic switch as an element of a security system may be affected by the alignment of the permanent magnet with the magnetic sensor and the sensitivity of the magnetic sensor. For example, if the permanent magnet is not within the magnetic sensor's reliable detection range when a door is in an expected position, then the magnetic sensor may incorrectly indicate that the door is not in position. Further, a misaligned permanent magnet may inadvertently be within the detection range of the magnetic sensor when the door is not in the expected position and therefore incorrectly indicate that the door is in position (e.g. a partially closed door indicated as fully closed).